1. Field
The present disclosure relates to a lithium ion secondary battery and a method for manufacturing the lithium ion secondary battery.
2. Description of the Related Art
Lithium ion secondary batteries have a high capacity and a high energy density and reduction in their size and weight is easily achieved. Lithium ion secondary batteries are widely used as power sources for mobile small-sized electronic devices, electric vehicles, and the like. The demand for lithium ion secondary batteries has been increasing year after year.
An important technical challenge in the development of lithium ion secondary batteries is increasing their capacity. Positive electrode materials that have been used to date are lithium-containing transition metal compounds represented by LixMeO2 (Me represents at least one selected from the group consisting of Co, Ni, Mn, and Al). For the purpose of increasing the capacity of LixMeO2, for example, studies are being conducted in which the charging voltage is increased and the surface structure is optimized (Japanese Unexamined Patent Application Publication Nos. 2006-185794 and 2007-66745). However, the amount by which the capacity of LixMeO2 can be increased in these studies is reaching the saturation point.